The principal aim of this research is to compare the effects of three drugs, secobarbital, meprobamate and methaqualone on human information processing. In the context of a serial-stage model, three laboratory tasks, Letter Transcription, Verbal Free Recall and Short-Term Recognition Memory, are employed, along with various task-related experimental variables, to identify the cognitive processes (stages) that are differentially vulnerable to each drug. Each drug is administered at three doses, over a range wide enough to separate drug effects from dose effects. If successful, these studies should reveal specific deficits produced by each drug and specify differences between related drugs within the framework of a common model of information processing. The results of these experiments will be compared with those already obtained in a completed series of studies of the effects of ethyl alcohol. BIBLIOGRAPHIC REFERENCES: Tharp, V.K., Rundell, O.H., Lester, B.K., and Williams, H.L. Alcohol and information processing. Psychopharmacologia (Berl.) 40, 33-52, 1974. Tharp, V.K., Rundell, O.H., Lester, B.K., and Williams, H.L. Alcohol and secobarbital: Effects on information processing. In: M. Gross (Ed.), Alcohol Intoxication and Withdrawal: Experimental Studies II, Advances in Experimental Medicine and Biology. Vol. 59, New York: Plenum Press, 1975.